This invention relates to digital photographic reproduction apparatus for producing a photographic image from digital image data.
With the development of digital cameras which produce digital files representative of photographed images, there is an increasing need for equipment for direct reproduction of images on photographic paper utilising the digital files produced by such cameras.
Digital photographic printing systems for this purpose are available commercially and are known commonly as photographic paperwriters. However such systems are costly and this renders their use uneconomical in many photoprocessing outlets. One type of photographic paperwriter which is commercially available makes use of a lens system to focus laser beams modulated by the digital data onto standard photographic paper in order to produce photographic colour prints at a rate of up to a thousand 8xc3x9710 inch prints per hour. However such equipment is large, complex and very expensive.
GB 2042746A discloses a multiple variable light source for a photographic printer incorporating an array of light-emitting diodes and a respective optical fibre associated with each light-emitting diode for conducting light from the diode towards the surface of a photoconductive drum. However such an arrangement suffers from the disadvantage that each individual fibre must have its end correctly aligned with respect to the associated light-emitting diode if acceptable photographic quality is to be achieved. Similar types of fibre optical array, suffering from the same disadvantage, are disclosed in WO 90/04194 and WO 90/04195.
It is an object of the invention to provide digital photographic reproduction apparatus which is capable of being produced at relatively low cost and of being used in such an application.
According to the present invention there is provided digital photographic reproduction apparatus for producing a photographic image from digital image data, the apparatus comprising carrier means for receiving a suitable photographic image carrier medium, an optical light pipe having a light receiving face at one end and a light transmitting face at an opposite end arranged to lie adjacent to the carrier medium, an array of light-emitting devices arranged adjacent the light receiving face of the light pipe, and digital control means for controlling the light-emitting devices so as to supply, in response to digital image data, optical writing signals which are transmitted along the light pipe to the carrier medium to produce a photographic image on the carrier medium, wherein the light pipe comprises a solid coherent bundle of optical fibres which is tapered in a region between the light receiving face and the light transmitting face so that the light receiving face has a substantially greater surface area than the light transmitting face to thereby increase the optical resolution of the photographic image.
Such digital photographic reproduction apparatus can be produced at much lower cost than currently commercially available systems, and can rapidly and accurately expose photographic paper to a digitally controlled image with a high degree of resolution, that is with a spot size of the order of {fraction (1/200)} to {fraction (1/800)} of an inch (120 to 30 xcexcm).
It should be understood that the terms xe2x80x9copticalxe2x80x9d and xe2x80x9clightxe2x80x9d as used in this specification are not intended to be limited simply to electromagnetic radiation in the visible part of the spectrum, and these terms are also to be considered as embracing within their scope electromagnetic radiation outside the visible part of the spectrum, such as infrared or ultraviolet light.